Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C13/00—Dental prostheses; Making same

Definitions

• This invention relates to the field of artificial dentures, and more particularly, to such dentures prepared from polyurethane elastomers and hard polymer components such as the hard acrylic resins and the hard epoxide resins.
• Isocyanate-terminated prepolymers suitable for preparing the hard non-hydrophilic polyurethane elastomers are prepared by the reaction of polyether diols or triols with aliphatic or cycloaliphatic or aralkyl di- or polyisocyanates in proportion to give free NCO groups.
• the prepolymers are then cured or cross-linked with a diol, polyol, an alkanolamine, a diamine or a tertiary amine containing polyol, or blends thereof.
• the diol or polyol is a polyether diol or polyol or a hydroxyl-terminated prepolymer.
• U.S. Pat. No. 4,225,696 to Colpitts, et al. which additionally is incorporated by reference herein, substitutes the aforementioned aliphatic, cycloaliphatic or aralkyl di- or polyisocyanates with aromatic polyisocyanates in which the isocyanate groups are bonded directly to the aromatic nucleus, e.g., 2,4-tolylene diisocyanate (TDI), isomeric mixtures of TDI, 3,3'-tolidene 4,4'-diisocyanate (TODI), 3,3'-dimethyldiphenylmethane 4,4'-diisocyanate, diphenylmethane 4,4'-diisocyanate (MDI), mixtures of MDI and adducts of MDI, etc.
• TDI 2,4-tolylene diisocyanate
• TODI 3,3'-tolidene 4,4'-diisocyanate
• MDI dipheny
• the resulting polyurethane can be fabricated into the soft, mouth-engaging portion of a denture possessing a relatively hard polymer as the tooth-engaging portion thereof.
• the hard polymer can be a hard polyurethane prepared in accordance with any of the aforesaid Colpitts, et al., patents or it can be any of the hard polymers heretofore used in the making of dentures.
• the acrylics, a class of relatively hard resins have for many years been used in the manufacture of prosthodontic devices and would be prime candidates for preparing composite polyurethane/hard polymer dentures in accordance with the teachings of U.S. Pat. No. 4,225,696 to Colpitts, et al.
• a denture which has a soft, mouth-engaging element to provide for the wearer's comfort and which at the same time is resistant to flex and photodegradation.
• an artificial denture of composite construction which comprises a tooth-holding portion fabricated from a hard non-polyurethane polymer having a hardness of not less than about Shore D40 integrally chemically bonded to a mouth-engaging portion fabricated from a soft non-hydrophilic polyurethane elastomer having a hardness of not greater than about Shore A65, said polyurethane being the reaction product of a polyether polyol and an aliphatic, cycloaliphatic or aralkyl di- or polyisocyanate in which the isocyanate groups are directly bonded to the aliphatic, cycloaliphatic or alkyl moieties thereof.
• the composite dentures of the present invention possess significant advantages over an all-polyurethane denture. Approximately 40% of all full and partial dentures currently being made possess acrylic teeth. Since in practice it is difficult to obtain a good chemical bond between acrylic teeth and polyurethane, the opportunities for debris (derived from foods, beverages, tobacco, etc.) to infiltrate crevices between the teeth and the polyurethane are much greater than in the case of acrylic teeth bonded to an acrylic tooth-holding portion.
• the hard acrylics as a class are generally quite stable to flex and are superior in this regard to an all-polyurethane denture whose mouth-engaging portion is prepared with an aliphatic, cycloaliphatic or aralkyl di- or polyisocyanate, it is particularly advantageous to mate the relatively flex-prone but photodegradation resistant soft polyurethanes as aforedescribed with the acrylics or, for that matter, with any other flex-resistant nonpolyurethane polymers such as the hard epoxide resins.
• the tooth-holding portion of the composite denture herein can be prepared from among any of the known and conventional hard acrylic resins employed in the manufacture of dentures, e.g., those having a hardness of at least Shore D40 and up to about Shore D100.
• the term "acrylic resin” as used herein is intended to include homopolymers of acrylic esters and acrylic amides of the general formula ##STR1## in which X is O or NH, R 1 is H or methyl and R is any of a wide variety of groups including aliphatic, cyclocloaliphatic, alkaryl, aralkyl, alkoxy, aryloxy, glycidyl, etc., groups, and copolymers of said esters/amides with other acrylic esters/amides and/or with one or more other copolymerizable ethylenically unsaturated monomers such as acrylonitrile, butadiene, styrene, vinyl acetate, and the like.
• Poly(methylmethacrylate) is an especially preferred resin for the tooth-holding portion of the composite denture herein because of the ready availability of the monomer, its low cost and its common use in dentistry.
• the techniques whereby acrylic resins can be fashioned into denture and partial dentures are well known, e.g., U.S. Pat. Nos. 3,251,910 and 3,258,509 to Barnhart both of which are incorporated by reference herein.
• the hard epoxide resins e.g., those having a hardness of at least Shore D40 and up to about Shore D100, which can be employed as the teeth-holding component of the dentures herein constitute a well known class of thermosetting resins.
• these resins are those derived from bisphenol A and epichlorohydrin cured with any of a variety of polyamines and specialty epoxy resins such as epoxy cresol novolac resins, epoxy phenyl novolac resins, bisphenol F-derived resins, polynuclear phenol-glycidyl ether-derived resins, cycloaliphatic epoxy resins, aromatic and heterocyclic glycidyl amine resins, tetraglycidylmethylenedianiline-derived resins, triglycidyl-p-aminophenol-derived resins, triazine-based resin and hydantoin epoxy resins.
• epoxy cresol novolac resins epoxy phenyl novolac resins
• bisphenol F-derived resins polynuclear phenol-glycidyl ether-derived resins
• cycloaliphatic epoxy resins aromatic and heterocyclic glycidyl amine resins
• the polyether polyols which can be used in preparing the mouth-engaging soft polyurethane portion of the composite denture herein can be selected from amongst any of the polyether polyols heretofore employed in the preparation of polyurethanes. Such polyols possess two, and preferably, three or more hydroxyl groups.
• polyether polyols include the poly-(oxypropylene) glycols, the poly-(oxypropylene) poly-(oxyethylene) glycols, the poly-(1,4-oxypropylene) glycols and graft copolymers of the poly-(oxypropylene) (polyoxyethylene) glycols with acrylonitrile or mixtures of acrylonitrile and styrene.
• the equivalent weight of these polyether diols can range between 200 to 100 with a preferred range of 200 to 400.
• the polyol may consist of simple polyfunctional alcohols such as glycerine, trimethylolpropane, 1,2,6-hexanetriol, or pentaerythritol, or they may consist of polyether triols such as poly(oxypropylene) or poly(oxyethylene) adducts of the above polyols.
• the equivalent weight of the polyether polyols may range between 100 to 800 with a preferred range of 100 to 500. It is also understood that various combinations of diols and polyols may be used.
• the polyisocyanates used for the preparation of the soft polyurethane elastomers must contain the isocyanate groups directly bonded to the aliphatic moieties thereof.
• Such isocyanates include, but are not limited to 4,4'-Dicyclohexylmethane diisocyanate, isophorone diisocyanate, 2,2,4-trimethyl-1,6-hexane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, "dimeryl” diisocyanate, methylcyclohexyl diisocyanate and the reaction product of 3 moles of hexamethylene diisocyanate with one mole of water (Desmodur N-triisocyanate).
• the ratio of NCO to OH in the preparation of the soft isocyanate-terminated prepolymer may range between 1.75 to 2.5 with a preferred range of 2.0 to 2.25.
• the soft isocyanate-terminated prepolymers should have a free NCO content of about 3.5 to 5.5 percent, preferably, 3.7 to 4.7 percent.
• preferred polyols are tertiary amine-containing polyols such as poly(oxypropylene) or poly(oxyethylene) adducts of diamines or triamines, such as ethylenediamine, diethylene triamine, tolylenediamine, phenylenediamine, or aniline, or any diols, polyols or their blends.
• tertiary amine-containing polyols such as poly(oxypropylene) or poly(oxyethylene) adducts of diamines or triamines, such as ethylenediamine, diethylene triamine, tolylenediamine, phenylenediamine, or aniline, or any diols, polyols or their blends.
• polyols of relatively low molecular weight such as are obtained by condensing propylene oxide with ethylenediamine or pentaerythritol to a molecular weight of about 500, or of trimethylolpropane or any other base compound to a molecular weight up to 2500.
• Another preferred curing or crosslinking agent is a hydroxyl-terminated prepolymer. These are prepared essentially the same way as the isocyanate-terminated prepolymers but the ratio is such that there are free and un-reacted hydroxyl groups.
• the same diols and polyol and isocyanates can be used, though it is preferred that the prepolymer have a functionality greater than 2, which can be obtained by using a polyol having a functionality greater than 2 and/or an isocyanate having a functionality greater than 2.
• the isocyanate is 2,2,4-trimethyl-1,6-hexane diisocyanate, hexamethylene diisocyanate or Desmodur N.
• the ratio of OH/NCO in the hydroxyl-terminated prepolymers advantageously may be in the same range as the NCO/OH ratio in the isocyanate-terminated prepolymers. It will be understood, however, that inasmuch as the crosslinking agent may consist of one or more diols or polyols (no isocyanate), the ultimate OH/NCO ratio is infinity.
• Another preferred curing or crosslinking agent is a prepolymer-polyol blend.
• a polyurethane prepolymer advantageously, one having neither free NCO nor free OH groups
• a polyol advantageously a polyol having a functionality of more than 2
• crosslinking is effected both through an NCO-OH reaction and through an NCO-urethane reaction.
• one or both adjoining surfaces is coated with a primer formulation prepared by mixing polyisocyanate with polyol and thereafter the two components are joined.
• a denture will be provided in which the hard and soft elements are permanently bonded to each other.
• metal catalysts such as tin catalysts, for example, dibutyltin dilaurate and stannous octanoate, can be used.
• Polymeg 1000 and Polymeg 2000 are charged into the reactor and the mixture heated to 70° C. It is demoisturized in vacuum for 2-3 hours until the evolution of bubbles ceases.
• the contents of the reactor are cooled and are packaged into one gallon or one quart lined containers. Dry nitrogen is used to maintain an inert atmosphere in the containers which are then tightly closed.
• Poly(oxytetramethylene) glycols Polymeg 2000 and Polymeg 1000, are charged into a reactor and demoisturized in vacuum for 2-3 hours upon a gentle stirring of 60-120 rpm at 70° C.
• the demoisturized glycol mixture is cooled down to 50° C., a dry nitrogen blanket is applied, and diisocyanate (Hylene W) is added.
• the catalyst is added in portions in order to speed up the reaction.
• the charge of the reactor should exotherm.
• the temperature of the reactants should not be allowed to go over 75° C.
• the NCO content should be checked by the n-dibutylamine titration method.
• the NCO content should be in the range of 3.3%. If the content of NCO higher than 3.7% is found, the heating should be continued for an additional hour at 70° C. after the addition of a small amount (0.005%) of the catalyst.
• the above soft isocyanate-terminated prepolymers are essentially linear.
• All the pigments are dispersed in 5% of the total polyol, Pluracol 355.
• a ball mill or roller mill or any well-dispersing high speed mill can be employed.
• the catalyst has to be added before application.
• the amount of the catalyst depends on the type of isocyanate-terminated prepolymer to be used. Usually 0.15-0.35% of the catalyst is added, based on the total weight of the polymer and on the type of the polymer and the reacting groups.
• the pigments are dispersed in 5% of the polyols; then all the remainder of the polyols is blended with the pigment dispersion. Afterwards the mixture is demoisturized by applying a vacuum and gentle heating at 60°-70° C.
• the catalyst has to be added before application.
• the amount of the catalyst depends on the type of isocyanate-terminated prepolymer to be used.
• the amount of the catalyst is in the range of 0.15-0.25% for the soft elastomer formulation, in the range of 0.30-0.35%.
• Poly(oxytetramethylene) glycol is charged into a reactor and demoisturized in vacuum for 2-3 hours upon gentle stirring at 60-120 rpm at 70° C. Then the vacuum is released under dry nitrogen, and the dry nitrogen blanket is retained during the reaction time.
• Desmodur N-triisocyanate is stirred in and reacted with the glycol until the NCO content is reduced to zero. Then Pluracol TP 1540 is blended in.
• the pigments are dispersed in a small amount of the triol, Pluracol TP 1540, and stirred in with the total content of the prepolymer-polyol blend.
• Components A and B are degassed and demoisturized for at least 1 hour at 60° C. and then blended gently with the catalyst and placed in a pre-heated vacuum oven for 1-2 minutes. They are then cast into a pre-heated denture mold containing a previously cast hard-non-hydrophylic polyurethane elastomer as above described and kept in an oven at 90° C. for 3 hours. The denture is then removed from the mold and finished by removing the sprues and flash and polishing as necessary.
• compositions of Examples 2 and 3 are degassed, demoisturized, blended, cast, and cured as in Example 1.
• Components A and B should be heated up to approximately 60° C. and degassed and demoisturized under vacuum before blending. Then the catalyst should be added. The blend should be cast into a preheated mold and heated with a mold release agent. The elastomer should be cured in an oven at 95° C. for 2 hours.
• a pre-formed hard acrylic denture supplied by a dental laboratory or dentist is provided with a mouth-engaging portion prepared with a soft polyurethane elastomer such as any of those described in Examples 1 to 4 above.
• the hard acrylic denture is placed in a flask such that the lowest portion of the denture is even with the flask. Investment material is then introduced into the flask even with the top of the flask. After the investment has set-up, a mold release agent is applied to all surfaces, i.e., investment, denture and teeth. After the mold release agent has dried (approximately five minutes), additional investment material is applied to cover the entire denture. The flask is then completely sealed by fastening a lid thereon. The flask is separated and the denture removed. The denture is then ground out to provide room for the soft polyurethane elastomer mouth-engaging portion.
• a plaster model is prepared in accordance with conventional dental laboratory procedures. Thereafter, the plaster model is sealed (i.e., a coating is placed on all exposed plaster surfaces except the bottom). The denture is then placed in a flask such that the lowest portion of the denture is even with the flask. Investment material is then introduced into the flask even with the top of the flask. After the investment has set-up, a mold release agent is applied to all surfaces, i.e., investment, denture and teeth.
• a primer e.g., 7.8 g Pep 550 (a polyether polyol from BASF Wyandotte having an average molecular weight of about 600 and a hydroxyl number of 448 and which is based on pentaerythritol oxyalkylated with propylene oxide) mixed with 7.3 g Hylene W (DuPont's 4,4'-dicyclohexylmethane diisocyanate) is applied to all surfaces of the denture where the soft elastomer is to adhere.
• the blockout material is removed from the plaster model. Mold release is again applied to the mold and plaster model and permitted to air-dry (approximately five minutes).
• the primed denture is then inserted in the mold cavity.
• Liquid soft polyurethane formulation is introduced into the mold cavity and low spots on the plaster mold.
• the entire mold assembly is placed in a clamp and the clamped mold is placed in an oven heated to 85° C. After about three hours, the assembly is removed from the oven and cooled until comfortable to the touch.
• the mold is opened and the denture is removed from the investment and plaster model. The denture is thereafter trimmed, polished, etc., to provide the finished product.

Landscapes

• Health & Medical Sciences (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Dentistry (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Dental Preparations (AREA)
• Polyurethanes Or Polyureas (AREA)
• Dental Prosthetics (AREA)

Priority Applications (9)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22944384

Family Applications (1)

Country Status (9)

Cited By (5)

Families Citing this family (3)

Citations (6)

• 1981
  • 1981-03-31 US US06/249,643 patent/US4360344A/en not_active Expired - Fee Related
• 1982
  • 1982-11-09 SE SE8206357A patent/SE451532B/sv not_active IP Right Cessation
  • 1982-11-16 AU AU90607/82A patent/AU9060782A/en not_active Abandoned
  • 1982-11-17 GB GB08232841A patent/GB2130886A/en not_active Withdrawn
  • 1982-11-19 DE DE19823242850 patent/DE3242850A1/de not_active Withdrawn
  • 1982-11-22 JP JP57205328A patent/JPS5995209A/ja active Pending
  • 1982-11-22 BE BE0/209535A patent/BE895093A/fr not_active IP Right Cessation
  • 1982-11-22 FR FR8219514A patent/FR2536273A1/fr not_active Withdrawn
  • 1982-11-22 NL NL8204540A patent/NL8204540A/nl not_active Application Discontinuation

Patent Citations (7)

Also Published As

Similar Documents

Legal Events